(1). Field of the Invention
An intermetal dielectric using spin-on-glass etchback and method of forming the intermetal dielectric using spin-on-glass etchback. More specifically using an oxide cap layer, formed by means of plasma enhanced chemical vapor deposition, to isolate an intermetal oxide layer, formed using plasma enhanced tetra-ethyl-ortho-silicate, from SOG spacers.
(2). Description of Related Art
In integrated circuit elements using dense electrode patterns where spaces between electrodes is very small spin-on-glass, SOG, is often used as a spacer material to provide good step coverage over the electrodes. Additional oxide layers are then used to form the intermetal dielectric, IMD. It is desirable to use an oxide layer formed using plasma enhanced tetra-ethyl-ortho-silicate, PE-TEOS, as an additional oxide layer to form the IMD however when an oxide formed using PE-TEOS and SOG make direct contact device function and reliability are adversely affected. This invention uses a oxide cap layer formed using PE-CVD to isolate the oxide layer formed using PE-TEOS from the SOG.
U.S. Pat. No. 5,252,515 to Tsai et al. describes methods for forming a SOG sandwich structure with two layers under the SOG layer but does not describe using an oxide cap layer to isolate SOG form an oxide layer formed using PE-TEOS.